Yield, protein, and oil quality of soybean genotypes selected for tofu production.

The soyfood industry prefers some soybean [(Glycine max L. (Merr.)] cultivars over others based on chemical constituents, physical traits, and processing quality of the seed. However, soybean cultivars possessing the combination of desirable agronomic traits and biochemical characteristics that enhance the quality of soyfoods have not been identified in the USA. Thus, this research was conducted with the objective of determining yield, seed protein, and fatty acid composition of soybean genotypes selected for tofu production. Twelve soybean genotypes were planted in plots arranged in a randomized complete block design with four replications at the Agricultural Research Station, Fort Valley State University, Georgia, USA during 1994 and 1995. Seed yield ranged from 1.6 to 3.0 metric tons/ha. The protein content varied between 314.2 and 480.7 g/kg seed. Both BARC-8 and BARC-9 had significantly higher protein content than other genotypes. These two genotypes also showed significant year by genotype interactions for some fatty acids. V71-370 had the highest oleic acid concentration and a high ratio (0.92) of monounsaturated to polyunsaturated fatty acids. The concentration of linoleic and linolenic acids ranged from 406.5 to 531.0 and 37.1 to 63.0 g/kg oil, respectively. Seed yield was correlated with biomass, harvest index, and filled pods per m2. In this study, V71-370 was found to be relatively superior in oil quality with fatty acid composition desirable for human consumption. The significant variation for seed yield and biochemical characteristics observed among the few genotypes examined in this study indicates the potential for breeding high yielding soybean cultivars suitable for soyfoods. Therefore, there is a need for evaluation of soybean germplasm for agronomic traits that contribute to seed yield and biochemical characteristics including fatty acid profiles that enhance soyfood quality before initiating development of suitable cultivars for tofu.